package com.wc.AlgoOJ_train.train1.c9.A901;

import java.io.PrintWriter;
import java.util.Scanner;

/**
 * @Author congge
 * @Date 2024/1/11 21:48
 * @description 交互题入门
 * http://43.138.190.70:8888/p/A901
 */
public class Main {
    static PrintWriter out = new PrintWriter(System.out);

    public static void main(String[] args) {
        long left = -(long) 1e18;
        long right = (long) 1e18;
        long guess = 0;
        Scanner sc = new Scanner(System.in);
        while (left <= right) {
            guess = (left + right) >> 1;
            out.println("? " + guess);
            out.flush();
            char res = sc.next().charAt(0);
            if (res == '=') {
                out.println("! " + guess);
                break;
            } else if (res == '>') {
                left = guess + 1;
            } else {
                right = guess - 1;
            }
        }
        out.flush();
    }
}
